In a solar cell production process, visual inspection for inspecting cracking, chipping, pattern defects, deposited film defects, and the like of solar cells, and internal inspection for inspecting cracks and voids occurring inside solar cells are performed.
Patent Literature 1 discloses a defect inspection apparatus that inspects a defect in the surface of a semiconductor wafer by irradiating the semiconductor wafer with a laser beam from a laser light source, and also imaging an optical image reflected by the surface of the semiconductor wafer by an imaging device to extract the defect from image data on the semiconductor wafer imaged by a defect detecting part.
Also, Patent Literature 2 discloses an infrared inspection apparatus that irradiates a semiconductor wafer with infrared rays from an infrared light source, and also images infrared rays transmitting through the semiconductor wafer by an infrared camera. This infrared inspection apparatus is configured to detect a microcrack inside the semiconductor wafer by utilizing the difference in transmission state of the infrared rays between an abnormal part such as a crack and a polysilicon substrate part.